1. Field of the Invention
The present invention relates to a voltage compensation circuit and a semiconductor integrated circuit device. More particularly, the present invention relates to a voltage compensation circuit that can compensate for an abrupt change in an internal power supply voltage, and a semiconductor integrated circuit device including such a circuit.
2. Description of the Background Art
A conventional internal voltage-down converter included in a semiconductor integrated circuit device will be described with reference to FIG. 5.
A conventional internal voltage-down converter 900 of FIG. 5 includes a comparator 27 and a PMOS transistor 29. Comparator 27 has a positive input receiving an internal power supply voltage Vout from an output node Z0 of internal voltage-down converter 900, and a negative input receiving a reference voltage Vin. Comparator 27 compares reference voltage Vin with internal power supply voltage Vout.
PMOS transistor 29 connected between power supply voltage Vdd and output node Z0 has a gate electrode connected to comparator 27. PMOS transistor 29 is turned on/off in response to the output (comparison result) of comparator 27. Output node Z0 is charged when PMOS transistor 29 is turned on. Accordingly, the level of voltage Vout of output node Z0 is adjusted.
In the conventional internal voltage-down converter 900 of the above structure, the ripple rejection is improved as the difference between the power supply voltage and the output voltage becomes greater.
The need arises for a semiconductor integrated circuit device to operate using a further lower voltage in order to satisfy the demands of higher integration density. The operating environment of a conventional voltage-down converter is getting more severe.
There was a problem that the level of internal power supply voltage Vout cannot be recovered to the level of the intended reference voltage Vin with respect to an abrupt change in internal power supply voltage Vout.